Bis(amido)cyclodiphosph(III)azane Complexes of Yttrium and the Lanthanides |
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| Authors: | Marcus Rastätter Dr Roberto?B Muterle Peter?W Roesky Prof?Dr Sven K‐H Thiele Dr |
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| Institution: | 1. Institut für Chemie und Biochemie, Freie Universit?t Berlin, Fabeckstrasse 34‐36, 14195 Berlin (Germany);2. Institut für Anorganische Chemie, Universit?t Karlsruhe (TH), Engesserstr. 15, 76128 Karlsruhe (Germany), Fax: (+49)?721‐608‐4845;3. Dow Olefinverbund GmbH, Synthetic Rubber Business, PF1163, 06201, Merseburg (Germany) |
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| Abstract: | The first cyclodiphosph(III)azane complexes of the rare‐earth elements have been synthesized. Reactions of the lithium salt cis‐(tBuNP)2(tBuN)2{Li(thf)}2] with anhydrous yttrium trichloride or the heavier lanthanide trichlorides resulted in the corresponding cyclodiphosph(III)azane complexes Li(thf)4]{(tBuNP)2(tBuN)2}LnCl2] (Ln=Y ( 1 a ), Ho ( 1 b ), Er ( 1 c )). The single‐crystal X‐ray structures showed that compounds 1 a – c consisted of ion pairs composed of a Li(thf)4]+ cation and a C2v symmetric {(tBuNP)2(tBuN)2}LnCl2]? anion. By treating cis‐(tBuNP)2(tBuN)2{Li(thf)}2] with anhydrous SmCl3 in THF, the trimetallic complex {(tBuNP)2(tBuN)2}SmCl3Li2(thf)4] ( 2 ) was obtained. The influence of the ionic radii of the lanthanides can be seen in the single‐crystal X‐ray structure of compound 2 , which forms a six‐membered Cl‐Li‐Cl‐Li‐Cl‐Sm metallacycle. The ring adopts a boat conformation in which one chlorine atom and the samarium atom are displaced from the Cl2Li2 least‐square plane. Heating of the metalate complexes in toluene resulted in the extrusion of lithium chloride and the formation of the neutral dimeric metal chloride complexes of the composition (tBuNP)2(tBuN)2LnCl(thf)]2 (Ln=Y ( 3 a ), La ( 3 b ) Nd ( 3 c ), Sm ( 3 d )). Furthermore, treating 1 a with KNPh2 resulted in a lithium metalate complex of the composition Li(thf)4]{(tBuNP)2(tBuN)2}Y(NPh2)2] ( 4 ). The coordination mode of the {(tBuNP)2(tBuN)2}2? ligand in 4 is different to that observed in 1 a – c , 2 , and 3 a – d ; instead of a symmetric η2 coordination of the ligand, a heterocubane‐type structure is observed in the solid state. The complex (tBuNP)2(tBuN)2NdCl(thf)] ( 3 c ) was used as a Ziegler–Natta catalyst for the polymerization of 1,3‐butadiene to poly‐cis‐1,4‐butadiene. The observed activities of the Ziegler–Natta catalyst strongly depended upon the nature of the cocatalyst; in some case very high turnover rates and a cis selectivity of 93–94 % were observed. |
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| Keywords: | cage compounds chelates lanthanides N P ligands polymerization |
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